This invention relates to elongated structures, such as a catheter implanted in tissue or an electrical pacemaker or defibrillator lead implanted in or on the heart and, particularly, to apparatus for removing such elongated structures implanted in biological tissue.
A heart pacemaker is generally implanted subcutaneously in the chest wall along with a coiled structure such as an electrical wire coil lead for conducting electrical signals such as stimulating and sensing signals between the pacemaker and the heart. The lead is surgically implanted through a vein leading to a cavity of the heart. A typical lead includes one or more helical wire coils having a hollow inner passageway that extends the entire length of the wire coil. The coiled structures are positioned in the lead either coaxially or laterally. The wire coils are surrounded by an insulating material such as a flexible tube, sheath, or coating comprising, for example, silicone or polyurethane for insulating the wire coils from body fluids as well as each other. However, one problem is that, over time, fibrotic tissue commonly encapsulates the pacemaker lead especially in areas where there is low velocity blood flow. When small diameter veins through which the lead passes become occluded with fibrotic tissue, separating the lead from the vein is difficult and causes severe damage or destruction of the vein. Furthermore, the separation is usually not possible without restricting or containing the movement of the pacemaker lead.
In most cases, the useful life of a pacemaker lead lasts for many years. However, should the pacemaker lead become inoperative or should another heart lead be desired, the existing pacemaker lead is typically left in place, and a new pacemaker lead is implanted. One problem with leaving an implanted lead in place, particularly in the heart, is that the lead actually restricts the operation of the various heart valves through which the lead passes. If several leads passing through a heart valve are left in place, the operation of the heart valve and the efficacy of the heart is significantly impaired.
Another problem associated with leaving a pacemaker lead in place, particularly in blood vessels, is that an infection may develop in or around the lead, thereby requiring surgical removal. Surgical removal of the lead from the heart often involves open heart surgery with accompanying complications, risks, and significant cost.
One method for transvenous removal of a pacemaker lead involves a prior art heart lead removal tool that utilizes a hollow, rigid tube and a beveled rod tip for engaging and deforming the coiled structure of the heart lead. However, when the lead cannot be removed because of some complication, a serious problem is that the tip of the tool is locked in place and cannot be removed from the lead. As a result, the tool and lead must be surgically removed. Furthermore, the rigid tube of the tool can easily puncture a blood vessel or, even worse, a heart cavity wall.
Another method is to transvenously extract the lead manually without the aid of a tool. Such method is possible only when the lead has not been encapsulated in or restricted by a blood vessel. Even then, this method has a number of problems. First, when the polyurethane or silicon insulation surrounding the wire coil is damaged, the insulation can sever and cause the coiled structure of the lead to unwind and possibly to damage the heart and surrounding blood vessels. Secondly, when both the coiled structure and insulation are severed in the heart or a blood vessel, surgical removal is required. Thirdly, most pacemaker leads typically include tines or a corkscrew at the tip or a conically shaped tip for securing the distal end of the pacemaker lead to a heart cavity wall. For fibrotic tissue that has encapsulated the tip, unaided manual removal of the heart lead from the heart cavity wall may cause an inward extension or inversion of the wall, or even worse, permanent damage to the heart such as tearing a hole in the heart cavity wall.
There a several different systems for lead removal that involved advancing a stylet into the coiled electrode and securing the electrode near the tip of the lead to facilitate its removal. The LEAD EXTRACTION(trademark) System (Cook Vascular Inc., Leechburg, Pa., described U.S. Pat. No. 4,988,347, entitled xe2x80x9cMethod and Apparatus for Separating a Coiled Structure from Biological Tissuexe2x80x9d, Filed Nov. 9, 1988, and related subsequent patents) is particularly well-suited for the removal of a pacemaker lead implanted in the heart and encapsulated in vessels connecting with the heart. Others devices by Vascomed and Spectranetics have entered the market in the U.S. and/or Europe. While the use of a radially expandable wire coil at the distal end of a stylet is an effective method of securing the pacemaker lead near the electrode tip, failure to engage has been observed in a number of cases. In an expandable wire coil system, correct sizing of the lead coil is critical prior to introduction of the locking stylet. Nevertheless, behavior of the wire coil during expansion can be unpredictable so that even when the correct locking stylet is selected, adequate engagement with the lead coil often cannot be achieved, or the two can separate during traction to free the lead. While often this may occur due to improper locking technique on the part of the physician, often the failure is purely mechanical. Many times, a second locking stylet can be used successfully, but this results in increased material costs and risk to the patient due to the lengthening of the procedure.
Another disadvantage of currently available systems is that array of different sized stylets must be used for the wide range of pacemaker electrode sizes, normally 0.016 to 0.032xe2x80x2xe2x80x3. Having to properly size the coil for selection of the optimal stylet adds time, cost, and the potential for error to the procedure. What is needed is a single locking stylet that can expand to engage and remove any standard pacemaker lead, regardless of the electrode coil size.
The foregoing problems are solved and a technical advance is achieved with illustrative lead removal apparatus for removing an implanted, cardiac pacemaker lead. The pacemaker lead includes, as previously suggested, a coiled structure such as an electrical wire coil for conducting electrical signals between the pacemaker and the heart. This coiled structure typically has a hollow inner passageway that extends longitudinally therethrough. The wire coil is surrounded by insulating material for insulating the wires from body fluids. The lead removal apparatus includes control means having a distal end for insertion into the passageway of the coiled structure. The lead removal apparatus also includes expandable means positioned proximate the distal end of the control means. The expandable means also has an expanded position in the coiled structure passageway for securing the control means to the coiled structure for removal of the implanted lead from the heart.
In one aspect, the control means comprises actuator means for expanding the expandable means to the expanded position when the expandable means is positioned in the passageway of the coiled structure. The expandable means also includes a relaxed position for positioning the lead removal apparatus in the coiled structure passageway.
In another aspect, the control means includes an outer tube and an actuator rod insertable through the outer tube. The expandable means includes a barb positioned proximate the distal end of the outer tube. When the actuator rod is positioned proximate the distal end of the outer tube, the rod expands the barb to the expanded position.
In another aspect, the expandable means includes a slotted sleeve positioned between the distal ends of the outer tube and the actuator rod. The ends of the tube and rod engage the slotted sleeve when expanding the slotted sleeve to an expanded position, which hooks into the coiled structure for securing the actuator rod to the coiled structure. The distal ends of the rod and the outer tube are beveled for easing expansion of the slotted sleeve when the actuator rod is withdrawn from the outer tube.
In still another aspect, the expandable means includes an expandable pliable material sleeve between the distal ends of the outer tube and the actuator rod. The pliable material sleeve comprises, for example, a pliable material such as synthetic rubber and the like, which expands in a radial direction when compressed between the distal ends of the outer tube and the actuator rod to frictionally engage the coiled structure and secure the outer tube and actuator rod thereto. In another configuration, the pliable material sleeve has an outside dimension greater than the coiled structure passageway when the sleeve is in a relaxed position. The sleeve is stretched between the distal ends of the outer tube and actuator rod to reduce its outer diameter, which is then insertable into the coiled structure passageway.
In yet another aspect, the expandable means of the lead removal apparatus includes projection means proximate a distal end of the outer tube for hooking into the coiled structure. The control means further includes a stylet for engaging and urging the projection means into the coiled structure when positioned in the coiled structure passageway.
The lead removal apparatus may also be characterized as comprising tube means having a distal end for inserting into the passageway of the coiled structure, expansion means positioned proximate a distal end of the tube means for hooking into the coiled structure of the pacemaker lead; and stylet means insertable into the tube means for engaging the expansion means. As previously suggested, the tube means includes an outer tube having a passageway extending longitudinally therethrough. The stylet means includes a wire extending through the outer tube passageway. And the expansion means includes a projection proximate the distal end of the outer tube hooking into the coiled structure when positioned in the coiled structure and expanded outwardly from the outer tube.
The lead removal apparatus may also be characterized as comprising an outer tube having a passageway extending longitudinally therethrough, which is sized for insertion into the passageway of the coiled structure; an anchoring projection positioned proximal the distal end of the outer tube; and a stylet positioned through the outer tube passageway and urging the anchoring projections between relaxed and hooked positions. In the hooked position, the anchoring projection extends outwardly from the outer tube and when also positioned in the coiled structure passageway hooks into the coiled structure. In the relaxed position, the anchoring projection is insertable into the coiled structure passageway for positioning therein.
The foregoing problems are also solved and a technical advance is achieved with illustrative apparatus for removing an elongated structure such as a catheter or an electrical pacemaker lead implanted in biological tissue such as a blood vessel or a heart cavity wall. The illustrative apparatus includes a control unit having a longitudinal passageway such as a flexible tube that is insertable in the longitudinal passageway of the catheter or the wire coil of the pacemaker lead for controlling movement of the elongated structure. Positioned about the distal end of the control unit is an expandable unit that is operable to a position for securing the control unit to the elongated structure. The control unit passageway is used for operating the expandable unit.
In a first embodiment, the control unit is a flexible tube with one or more side ports or apertures for passing a fluid therethrough for operating the expandable unit. In this embodiment, the expandable unit is a balloon attached about the distal end of the tube with the side ports leading from the passageway for inflating or expanding the balloon to an expanded position for securing the control unit to the elongated structure.
In a second embodiment, the control unit again includes a flexible tube. The expandable unit includes a number of twisted radial projections each having a free end that is formed from radial strips cut in the distal end of the tube. The strips are twisted at the free end and pushed into the passageway of the tube. The apparatus further comprises an actuator such as a rod that is inserted into the passageway of the tube to engage and expand the free end of the projections into the wire coil of the pacemaker lead, thereby securing the control tube to the wire coil.
In a third embodiment, a plurality of expandable strips are longitudinally formed in the distal end of the control tube. The actuating rod of the apparatus is inserted in the tube passageway and attached at the distal end of the tube. When the apparatus is inserted in the passageway of the elongated structure, the actuator rod is pulled in a direction out of the tube while operating the deformable strips into an expanded position engaging the wall of the structure passageway for securing the control tube to the elongated structure.
In a fourth embodiment, a number of barbs or a helical ridge is formed at the end of the control tube. The expandable distal end of the control tube is partially collapsed or formed such that the barbs or ridge when expanded by an actuator rod extend beyond the nominal diameter of the tube. The actuator rod is extended through the tube passageway to expand the distal end of the tube and cause the barbs or ridge to engage the structure and secure the control tube thereto.
In a fifth embodiment, the apparatus also includes a hollow control tube having a longitudinal passageway therein. An expandable slotted sleeve is positioned at the distal end of the control tube. An actuator rod is inserted through the slotted sleeve and control tube. The distal end of the rod is enlarged to engage and expand the slotted sleeve against the distal end of the control tube. When inserted in the passageway of the elongated structure, the actuator rod is pulled in a direction out of the control tube passageway to force the enlarged distal end of the rod into the passageway of the slotted sleeve and expand the slotted sleeve into the wall of the elongated structure. As a result, the control tube is secured to the elongated structure for controlling the movement thereof.
In sixth and seventh illustrative embodiments similar in function to the fifth embodiment, an expandable sleeve comprising a pliable material is positioned between the distal ends of the control tube and actuating rod. In the sixth embodiment, the pliable material sleeve is compressed between the distal ends of the control tube and actuator rod to expand and engage the passageway walls of the elongated structure. In the seventh embodiment, the pliable material sleeve is already in an expanded position to engage the passageway walls of the elongated structure. To insert this expanded pliable material sleeve into the passageway of the elongated structure, the actuator rod is pushed into the passageway of the control tube to longitudinally stretch the pliable material sleeve. As a result, the outside diameter of the sleeve is compressed to allow the apparatus to be inserted into the passageway of the elongated structure. When inserted, the actuator rod is released allowing the sleeve to radially expand and engage the wire coil or passageway walls of the elongated structure.
The invention is further directed to removal apparatus having a guide that is insertable into the passageway of the elongated structure for guiding the control unit in the passageway. In those instances where the passageway of the elongated structure has become blocked or occluded, the apparatus advantageously includes this guide for breaking through the occlusion. Furthermore, various diameter guides are inserted into the structure passageway for determining the minimum passageway diameter of the structure when the structure has in some way been deformed or damaged. Illustratively, the guide includes a stylet wire that is first inserted into the passageway of the elongated structure. When the stylet guide has been inserted, the control tube is inserted over the proximal end of the stylet wire and inserted into the passageway of the structure. In one embodiment, the expandable unit of the apparatus includes a wire coil positioned around and attached at its distal end to the control tube. When inserted, the control tube is rotated to expand the wire coil and secure the control tube to the elongated structure.
In another embodiment, the expandable unit includes a balloon attached about the distal end of the control tube. The control tube includes a second passageway that leads to the balloon for inflating the balloon to secure the control tube to the passageway wall of the elongated structure.
The invention is also directed to a removal apparatus having a rotatable unit for securing the control unit to the elongated structure. In one illustrative embodiment, the removal apparatus includes a control tube insertable into the passageway of the elongated structure for controlling the movement thereof. Positioned about the distal end of the control tube is a rotatable unit such as a cylindrical rod that is rotatable to a position off-centered from the tube for securing the control tube to the elongated structure. The apparatus also includes an actuator rod extending through the control tube and attached off-centered to the cylindrical rod for rotating the rod into the off-centered position securing the control tube to the structure.
The invention is still further directed to removal apparatus having a control tube that is insertable into the passageway of the elongated structure and has an extended projection at the distal end thereof for securing the tube to the structure. Also included is a stylet that is insertable into the passageway of the tube for operating the extended projection to a retracted position for insertion or removal of the control tube from the passageway of the elongated structure.
The invention also includes apparatus for separating the elongated structure from tissue that is restricting the movement and, consequently, the removal of the elongated structure. In one illustrative embodiment, the separating apparatus includes a tube having a first passageway for receiving the elongated structure. Positioned about the distal end of the tube is a balloon that is inflatable for separating restricting tissue from a length of the elongated structure. A second passageway extending along the tube and to the balloon is included for inflating the balloon.
In another embodiment, the separating apparatus includes a first tube having a passageway for receiving the elongated structure and a distal end for separating the structure from the restricting tissue as the elongated structure is received into the passageway. Also included is a second tube having a passageway for receiving the elongated structure and the first tube for separating the restricting tissue from either the first tube or the elongated structure. Advantageously, at least one of the two tubes comprises a polypropylene material, which is much less susceptible to kinking than teflon. In operation, two tubes are alternately moved along the elongated structure to provide tissue separation. The second tube advantageously adding strength to the removal apparatus for separating the restricting tissue. A control mechanism having a passageway for passing the proximal end of the elongated structure therethrough is also attached to the proximal end of the first tube for controlling movement of the first tube in either a rotational or longitudinal direction about the elongated structure. To facilitate visualization of the separating apparatus in biological tissue such as a blood vessel, at least one of the two tubes includes a radio-opaque material such as bismuth.
The invention also includes apparatus for separating the distal end of an elongated structure such as a pacemaker lead from heart tissue affixed thereto. In one illustrative embodiment, the separating apparatus includes first and second concentric tubes each having a passageway for receiving the structure to the distal end thereof. An elongated member such as stainless steel wire or suture material is extendable between the distal ends for cutting the distal end of the structure from the tissue. When the tubes are positioned at the distal end of the coiled structure, the tubes are rotated in opposite directions to wipe the wire or suture material across the distal ends of the tubes and structure, thereby cutting the distal end of the structure from the affixed tissue. At least one of the tubes also has a second passageway or channel for controlling the amount and the tension of the elongated means at the distal ends thereof.
In a second illustrative embodiment, the separating apparatus includes a tube having a passageway for receiving the lead. The distal end of the tube is extendable to the distal end of the pacemaker lead. Included at the distal end of the tube is a plurality of slots for receiving the tines of the pacemaker lead. When the tines have been positioned in one or more of the slots, the tube is rotated for separating the tines and distal end of the lead from the encapsulating tissue.
The invention is further directed to apparatus for expanding the proximal end of a severed coiled structure of a pacemaker lead. Advantageously, this expands the wire coil structure of a pacemaker lead to insert a sizing stylet or gauge to accurately determine the diameter of the wire coil of the pacemaker lead. When the connector end is severed from the proximal end of the pacemaker lead, the severing operation deforms the wire coil and provides a false indication of the true diameter of the passageway extending to the distal end of the lead. The expanding apparatus includes a tapered rod having distal end with a first diameter that is easily insertable into a passageway of the coiled structure of the pacemaker lead. The rod has a tapered longitudinal portion extending from the distal end to a proximal end having a second diameter greater than the first diameter. The tapered portion engages and expands the proximal end of the severed coiled structure when inserted therein. The apparatus also includes a control mechanism attached to the rod for controlling movement of the rod in the passageway of the coiled structure.
The invention includes apparatus for removing an elongated coiled structure implanted in biological tissue such as the wire coil of a pacemaker lead implanted in the heart through a blood vessel leading thereto. The apparatus includes a stylet wire that is insertable into a longitudinal passageway of the coiled structure for controlling movement of the structure. A wire coil is attached at its distal end to the distal end of the stylet wire and is expandable for securing the stylet wire to the coiled structure. The proximal end of the wire coil is extended from the wire coil and stylet wire for engaging the coiled structure and for controlling expansion of the wire coil.
In another illustrative embodiment of this removal apparatus, first and second coil means, such as a wire coil having respective first and second pluralities of turns, are positioned about the distal end of the stylet wire. The first coil means is attached about the distal end of the stylet wire and is radially expandable about the stylet wire for securing the stylet wire to the implanted lead when the stylet wire is inserted in the longitudinal passageway of the implanted lead. The second coil means extends proximally from the first coil means and laterally from the stylet wire for advantageously engaging the implanted lead and radially expanding the first coil means about the stylet wire. The second plurality of wire turns is formed to have a predetermined length and width for advantageously engaging the coil structure of the implanted lead. Furthermore, the second plurality of wire turns and stylet wire cooperatively have a cross-sectional dimension approximating that of the implanted lead passageway. The first coil means also includes a third plurality of closely-spaced wire turns that extends distally from the first plurality and that is positioned around and attached to the stylet wire. The second and third pluralities of wire turns cooperate to radially expand the first plurality of wire turns. An enhancement to this illustrative embodiment includes a flat and a tapered portion of the stylet wire that is positioned between the first and third pluralities of wire turns for unremovably engaging the coiled structure of the implanted lead. The width of this flat portion approximates the width of the implanted lead passageway. The tapered portion extends proximally from the flat portion for advantageously expanding the first plurality of wire turns within the passageway of the implanted lead. The tapered portion more quickly expands the first plurality of wire turns to engage the coiled structure of the implanted lead and secure it thereto without retraction of the stylet wire from the electrode of the implanted lead. In addition, the distal end of the stylet wire is tapered for easy insertion into the implanted lead passageway.
In another embodiment of the lead removal apparatus of the present invention, the lead removal apparatus preferably includes a tube, and control means for moving the coiled structure of a cardiac lead when secured to the coiled structure. The control means is slidably arranged in the tube and has a distal end that is configured for insertion into the passageway of the coiled structure. The expandable means is other than and separate from the control tube and is positioned proximate the distal end of the control means. The expandable means has an expanded position in the passageway of the coiled structure for securing the control means to the coiled structure such that there is a more secure lock or engagement with the coiled structure and there are advantageously fewer failures in the locking engagement, thereby providing a more reliable mechanical connection. This particular arrangement also further provides greater size tolerance when selecting an appropriate lead removal apparatus and advantageously provides a wider range of lead passageway sizes for a given stylet diameter. This configuration also provides for less dependence on physician technique and experience than the previously described coiled structure.
The expandable means of the lead removal apparatus advantageously includes a laterally flexible member that extends longitudinally and proximally from the distal end of the control means. The laterally flexible member advantageously thus has a proximal end for assuming an expanded position and engaging the turns of a coiled structure. The laterally flexible member is attached to the distal end of the control means and is further secured thereto with a sleeve positioned around the laterally flexible member and control means. In one embodiment, the control means comprises a stylet with the laterally flexible member including a folded-back portion or a plurality of folded-back portions of the stylet.
To facilitate fixing the relative positions of the stylet and outer tube, a lock is positioned at the proximal ends of the tube and stylet. For operation of the lead removal apparatus, handles are positioned proximate the proximal ends of the control tube and stylet.
The foregoing problems are solved and a technical advance is achieved in a lead removal apparatus that includes a locking stylet and a radially expandable portion that comprises a plurality of expandable members. A actuator portion, such as a elongate cannula or section or coiled wire, is advanced against the expandable portion, causing the latter to expand radially and engage the coils of the pacemaker lead into which it has been introduced. In one embodiment, the expandable portion comprises a wrap of multifilar wires (six to a bundle) that is helically wound around the distal portion of a stylet pull wire. The multifilar bundle is soldered together and also to the distal end of the stylet such that the expandable portion is longitudinally compressible. When compressed, the expandable members bow outward and form an irregular-shaped, tangled mass that presses outward against, and between the coils to provide positive engagement for subsequent retraction of the pacemaker lead. To prevent premature advancement of the actuator portion and expansion of the expandable member, an optional deployment guard, such as a severable ligature, can secure the actuator portion and stylet together, generally via their respective handles.
In another embodiment of the invention, the expandable portion comprises a series of longitudinally parallel wires that expand outward when deployed. In still another embodiment, the expandable portion comprises a slotted cannula in which the expandable members between the longitudinal slots bow outward to engage the coils of the pacemaker lead.
In yet another embodiment of the invention, the handle of the lead removal apparatus includes a proximal portion of the handle of a lead removal apparatus which is formed into a pre-shaped first configuration, such as a series of coiled loops. The coiled loops provide the operator with a greater ability to apply traction on the locking stylet and pacemaker lead and helping to maintain the proximal portion of the apparatus within the sterile field. The proximal portion can constrained into a second, sufficiently straight configuration that allows the operator to feed a medical device, such as a dilator sheath thereover, such as for disrupting scar tissue encasing the lead along the path of the vein.